FIG. 16 is a sectional view that schematically illustrates a conventional elastic-wave filter device. As shown in FIG. 16, elastic-wave filter device 101 includes first piezoelectric substrate 103, second piezoelectric substrate 105, and sealing member 106. First piezoelectric substrate 103 has first IDT (interdigital transducer) electrode 102 on its top face. Second piezoelectric substrate 105 is disposed such that its lateral face confronts a lateral face of first piezoelectric substrate 103, and has second IDT electrode 104 on its top face. Sealing member 106 includes first sealer 106A and second sealer 106B. First sealer 106A is formed such that it covers at least an underside of first piezoelectric substrate 103 and an underside of second piezoelectric substrate 105. Second sealer 106B covers at least the lateral faces of first and second piezoelectric substrates 103 and 105. On top of that, elastic-wave filter device 101 includes first pillar-like wiring electrode 107, first externally connecting terminal 108, second pillar-like wiring electrode 109, and second externally connecting terminal 110. First pillar-like wiring electrode 107 is formed above first piezoelectric substrate 103 and electrically connected to first IDT electrode 102. Second pillar-like wiring electrode 109 is formed above second piezoelectric substrate 105 and electrically connected to second IDT electrode 104. Second externally connecting terminal 110 is electrically connected to second pillar-like wiring electrode 109.
In the structure discussed above, sealing member 106 integrates first piezoelectric substrate 103 and second piezoelectric substrate 105 into one body.
The foregoing elastic-wave filter device 101 is structured such that the underside of first piezoelectric substrate 103 is flush with the underside of second piezoelectric substrate 105. In a case where first piezoelectric substrate 103 is thicker than second piezoelectric substrate 105. The foregoing structure produces a greater distance between a plane including the top face of substrate 103 and a plane including the top face of substrate 105. In other words, this structure produces a greater step “d” between the top face of first piezoelectric substrate 103 and the top face of second piezoelectric substrate 105. Assume that filter device 101 is mounted to a mother board (not shown), then first externally connecting terminal 108 and second externally connecting terminal 110 are desirably formed on planes flush with each other. To achieve the planes flush with each other, first pillar-like wiring electrode 107 needs to be different from second pillar-like wiring electrode 109 in height by the step “d”. Forming this difference complicates a manufacturing process of filter device 101.